U.S. patent application number 12/593679 was filed with the patent office on 2010-04-29 for aliphatic polyester series resin composition, aliphatic polyester series film, reflective film and reflective plate.
This patent application is currently assigned to MITSUBISHI PLASTICS, INC.. Invention is credited to Kazunari Katsuhara, Jun Takagi, Takayuki Watanabe.
Application Number | 20100104883 12/593679 |
Document ID | / |
Family ID | 39863519 |
Filed Date | 2010-04-29 |
United States Patent
Application |
20100104883 |
Kind Code |
A1 |
Watanabe; Takayuki ; et
al. |
April 29, 2010 |
ALIPHATIC POLYESTER SERIES RESIN COMPOSITION, ALIPHATIC POLYESTER
SERIES FILM, REFLECTIVE FILM AND REFLECTIVE PLATE
Abstract
A polyester series film and a reflective film are provided,
which realize excellent reflectivity, and moreover, also excel in
formability. An aliphatic polyester series resin composition, which
is an aliphatic polyester series resin composition containing an
aliphatic polyester series resin, a thermoplastic resin
incompatible with said aliphatic polyester series resin
("incompatible resin"), a compatibilizing agent and a fine powder
filler, said compatibilizing agent being a SEBS series compound or
a glycidyl metacrylate-ethylene series copolymer, or a mixture
thereof, is proposed, along with an aliphatic polyester series film
comprising a resin layer A formed from said aliphatic polyester
series resin composition.
Inventors: |
Watanabe; Takayuki; (Shiga,
JP) ; Katsuhara; Kazunari; (Shiga, JP) ;
Takagi; Jun; (Shiga, JP) |
Correspondence
Address: |
DARBY & DARBY P.C.
P.O. BOX 770, Church Street Station
New York
NY
10008-0770
US
|
Assignee: |
MITSUBISHI PLASTICS, INC.
Tokyo
JP
|
Family ID: |
39863519 |
Appl. No.: |
12/593679 |
Filed: |
March 27, 2008 |
PCT Filed: |
March 27, 2008 |
PCT NO: |
PCT/JP2008/000749 |
371 Date: |
September 29, 2009 |
Current U.S.
Class: |
428/480 ;
252/582 |
Current CPC
Class: |
C08L 23/0869 20130101;
B32B 27/20 20130101; C08K 5/29 20130101; G02B 5/0284 20130101; B29K
2023/12 20130101; B32B 27/08 20130101; C08K 3/013 20180101; G02B
5/0247 20130101; B29C 55/023 20130101; B32B 27/32 20130101; B32B
2307/734 20130101; C08L 23/02 20130101; C08L 67/04 20130101; B29K
2995/006 20130101; B29K 2067/046 20130101; B32B 2457/00 20130101;
Y10T 428/31786 20150401; B32B 2307/73 20130101; B29K 2995/003
20130101; C08L 67/04 20130101; B29K 2067/00 20130101; B32B 2457/202
20130101; B32B 2307/402 20130101; B32B 2307/416 20130101; B29C
55/143 20130101; B32B 27/36 20130101; B32B 2264/104 20130101; B32B
2264/102 20130101; C08L 23/02 20130101; C08L 67/04 20130101; G02B
5/0808 20130101; B32B 2307/54 20130101; B32B 2307/516 20130101;
G02B 5/02 20130101; C08J 5/18 20130101; C08L 23/0869 20130101; C08L
2666/02 20130101; C08L 2666/02 20130101; C08L 2666/02 20130101;
C08L 2666/04 20130101; B32B 7/12 20130101; C08L 53/02 20130101;
B32B 2270/00 20130101; C08J 2367/04 20130101 |
Class at
Publication: |
428/480 ;
252/582 |
International
Class: |
G02F 1/361 20060101
G02F001/361; B32B 27/08 20060101 B32B027/08 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 29, 2007 |
JP |
2007-087728 |
Claims
1. An aliphatic polyester series resin composition, which is an
aliphatic polyester series resin composition comprising an
aliphatic polyester series resin, a thermoplastic resin
incompatible with said aliphatic polyester series resin, a
compatibilizing agent and a fine powder filler, said
compatibilizing agent being a SEBS series compound or a glycidyl
metacrylate-ethylene series copolymer, or a mixture thereof.
2. The aliphatic polyester series resin composition according to
claim 1, wherein said aliphatic polyester series resin is a lactic
acid series polymer.
3. The aliphatic polyester series resin composition according to
claim 1, wherein said thermoplastic resin incompatible with said
aliphatic polyester series resin is a polyolefin series resin.
4. The aliphatic polyester series resin composition according to
claim 1, wherein said fine powder filler is one species or a
mixture comprising the combination of two or more species chosen
from the group of calcium carbonate, zinc oxide, barium sulfate and
titanium oxide.
5. The aliphatic polyester series resin composition according to
claim 1 further containing an anti-hydrolysis agent.
6. An aliphatic polyester series film provided with a resin layer A
formed from the aliphatic polyester series resin composition
according to claim 1.
7. The method of obtaining an aliphatic polyester series film
comprising the steps of: melting, film-forming and stretching
1.1-fold or more in at least one axial direction the aliphatic
polyester series resin composition according to claim 1.
8. The aliphatic polyester series film comprising: a resin layer A
formed from the aliphatic polyester series resin composition
according to claim 1, and a resin layer B formed from a aliphatic
polyester series resin composition B containing an aliphatic
polyester series resin and a fine powder filler, and, containing no
thermoplastic resin incompatible with said aliphatic polyester
series resin and no compatibilizing agent.
9. The aliphatic polyester series film according to claim 8,
wherein the content in fine powder filler in the resin layer A is
10 to 50 percent in mass with respect to the total mass of the
resin layer A, and the content in fine powder filler in the resin
layer B is 0.1 to 5 percent in mass with respect to the total mass
of the resin layer B.
10. The aliphatic polyester series film according to claim 8,
wherein the aliphatic polyester series resin of the resin layer B
is a lactic acid series polymer.
11. The aliphatic polyester series film according to claim 8,
obtained by melting and film-forming separately each said aliphatic
polyester series resin composition A and said aliphatic polyester
series resin composition B to be layered, and stretching the
obtained layered film 1.1-fold or more in at least one axial
direction.
12. The aliphatic polyester series film according to claim 6,
wherein the dynamic storage modulus is 1.0 GPa to 3.0 GPa as
measured by dynamic viscoelasticity measurement at 10 Hz frequency
and 23.degree. C. temperature.
13. A reflective film comprising the aliphatic polyester series
film according to claim 6.
14. The reflective film according to claim 13 used as a
constitutive member of a liquid crystal display, an illumination
instrument or an illuminated sign.
15. A reflective plate provided with a constitution wherein the
aliphatic polyester series film according to claim 6 is layered
against a metal plate or a resin plate.
16. The reflective plate according to claim 15 used as a
constitutive member of a liquid crystal display, an illumination
instrument or an illuminated sign.
Description
CROSS REFERENCE TO RELATED APPLICATION
[0001] This is the U.S. national phase application under 35 U.S.C.
.sctn.371 of International Patent Application No.
PCT/JP2008/000749, filed Mar. 27, 2008, which claims the benefit of
Japanese Application No. 2007-087728, filed Mar. 29, 2007. The
International Application was published on Oct. 23, 2008 as
International Publication No. WO/2008/126359 under PCT Article
21(2) the contents of these applications are incorporated herein in
their entirety.
TECHNICAL FIELD
[0002] The present invention relates to a reflective film and a
reflective plate that can be used as a constitutive member of a
liquid crystal display, an illumination instrument, an illuminated
sign and the like, furthermore, it relates to an aliphatic
polyester series resin composition that can be used suitably as a
material therefor.
BACKGROUND OF THE INVENTION
[0003] Reflective plates are being used in many fields, such as,
liquid crystal display devices to begin with, illumination
instruments and illuminated signs. Recently, particularly in the
filed of liquid crystal display devices, enlargement of the devices
and advancement of display capabilities have progressed, and by
supplying as much light as possible to liquid crystal an increase
in the capabilities of backlight units is sought. Therefore, all
the more excellent light reflectivity (also simply referred to as
"reflectivity") is sought of reflective plates, and in particular
of reflective films constituting reflective plates.
[0004] As methods to cause a film to express light reflectivity,
the method of including a white pigment into a film and the method
of mixing into a film constitutive resin, a thermoplastic resin
that is incompatible therewith, to form microscopic bubbles within
the film, are known.
[0005] As the former method, for instance, a method is disclosed in
Abstract and Claims of Publication No. WO2004/104077, in which an
aliphatic polyester series resin serves as a base resin, and at the
same time as titanium oxide is included as white pigment, the film
is stretched, thereby providing voids within the film to increase
further the light reflectivity.
[0006] A polyester series film is proposed as a film by the latter
method, comprising a resin composition containing in a polyester,
titanium oxide particles, a thermoplastic resin incompatible with
the polyester and, further, a polyoxyalkylene glycol series
compound and/or a compound containing a sulfonate group as a
compatibilizing agent (refer to Japanese Patent Application
Laid-Open No. 2000-355090).
[0007] In the former method, that is to say, the method of
including white pigment in a film to cause expression of light
reflectivity, increasing the amount of white pigment added is
effective in order to increase reflectivity further. However, in so
doing, the elastic modulus of the film becomes excessively high,
sometimes giving rise to problems when the reflective plate is
fold-processed. For instance, if the elastic modulus of a film
becomes excessively high, when a reflective plate formed by
layering a film over a metal plate is fold-processed, there is the
problem that strain remains inside the reflective plate and the
dimensions of the reflective plate change during use.
[0008] Meanwhile, in the latter method, as raising sufficiently the
dispersability of an incompatible thermoplastic resin is difficult,
there is the risk that the bubbles (voids) formed around the resin
become rough and the reflection capability becomes insufficient. In
addition, when these compounds are added, there is also the risk
that coloration of the film occurs, decreasing the reflection
capability. In addition, while multiplying the amount of bubbles
inside the film is effective in order to increase reflectivity
further, which also has an effect on the suppression of the elastic
modulus of the film, generally, it bears the problem that
film-forming ability and mechanical characteristics worsen.
[0009] In order to provide a reflective film and a reflective plate
allowing excellent reflectivity to be realized, which excels in
fold-processability, and further, also in film-forming ability, the
present invention proposes an aliphatic polyester series resin
composition and an aliphatic polyester series film for forming the
reflective film and the reflective plate.
SUMMARY OF THE INVENTION
[0010] The present invention proposes an aliphatic polyester series
resin composition, which is an aliphatic polyester series resin
composition containing a aliphatic polyester series resin, a
thermoplastic resin incompatible with the aliphatic polyester
series resin (hereinafter also referred to as "incompatible
resin"), a compatibilizing agent and a fine powder filler, the
compatibilizing agent being an SEBS series compound or a glycidyl
metacrylate-ethylene series copolymer, or a mixture thereof, and at
the same time proposes an aliphatic polyester series film provided
with a resin layer A formed from the aliphatic polyester series
resin composition.
[0011] In addition, an aliphatic polyester series film provided
with the above-mentioned resin layer A formed from the aliphatic
polyester series resin composition and a resin layer B formed from
an aliphatic polyester series resin composition B containing an
aliphatic polyester series resin and a fine powder filler and not
containing the incompatible resin and compatibilizing agent, is
proposed.
[0012] Note that, "film" generally refers to a thin and flat
product in which the thickness is extremely small compared to the
length and width, with the maximum thickness being limited
arbitrarily, and commonly provided in the form of a roll (Japanese
industry specification JIS K6900), and "sheet" generally refers,
according to definitions in JIS, to a thin, flat product, the
thickness thereof being generally small considering the length and
width. However, the boundary between a sheet and a film is not
clear and since there is no need in the present invention to
distinguish the two literally, in the present invention, "sheet" is
deemed included even when called a "film" and "film" is deemed
included even when called a "sheet".
[0013] According to the present invention, in addition to
refractive scatter due to a refractive index difference between an
aliphatic polyester series resin and a fine powder filler, light
reflectivity can be obtained from refractive scatter due to a
refractive index difference between an incompatible resin and the
fine powder filler, furthermore, refractive scatter due to a
refractive index difference between the aliphatic polyester series
resin and voids formed around the incompatible resin, and the like,
allowing excellent reflectivity to be obtained despite the
thinness.
[0014] In addition, since the elastic modulus of the film can be
adjusted to be low by voids formed around fine powder filler and
incompatible resin, fold-processability of the film is improved.
This also allows the effect of improving dimensional stability to
be obtained when the film is turned into a reflective plate.
[0015] In addition, SEBS series compounds, glycidyl
metacrylate-ethylene series copolymers, and mixtures thereof as
compatibilizing agents allow dispersability of incompatible resin
in the aliphatic polyester series resin to be raised effectively.
In particular, dispersability of incompatible resin in an aliphatic
polyester series resin that heat-melts at comparatively low
temperatures similarly to lactic acid series polymers can be raised
extremely effectively, occurrence of die drool (lump from
attachment and deposition on the port lip of an extruder, a T-die
and the like) and pimply skin (microscopic film defect) during
film-forming can be suppressed, allowing a film having satisfactory
product appearance to be manufactured stably and without giving
rise to perforation during stretching.
[0016] Thus, the aliphatic polyester series resin composition as
well as the aliphatic polyester series film proposed by the present
invention can be used suitably as materials for a reflective film
used as a constitutive member of, for instance, a liquid crystal
display, an illumination instrument, an illuminated sign and the
like. In addition, layering (laminating) the aliphatic polyester
series film on a metal plate or a resin plate, allows for suitable
use as a reflective plate used as constitutive material for liquid
crystal display, illumination instrument, illuminated sign and the
like.
DETAILED DESCRIPTION OF THE INVENTION
[0017] Hereinafter, a reflective film used as a constitutive member
of a liquid crystal display, an illumination instrument, an
illuminated sign and the like will be described as one example of
embodiment of the present invention; however the application of the
aliphatic polyester series resin composition as well as the
aliphatic polyester series film of the present invention is not
limited to such a reflective film.
[0018] In the present specification, when the expression "main
constituent" is used, unless specifically stated otherwise, it
comprises the meaning of allowing another constituent to be
contained in a range that does not impede the function of the main
constituent. In this case, without specifying the content
proportion of the main constituent, the main constituent (when two
or more constituents are the main constituents, the total amount
thereof) commonly occupies, in the composition, 50 percent in mass
or greater, preferably 70 percent in mass or greater and
particularly preferably 90 percent in mass or greater (including
100%).
[0019] In addition, in the present invention, when the expression
"X to Y" (X and Y are arbitrary numbers) is used, unless
specifically indicated otherwise, it includes the meaning of "X or
greater but Y or less" and at the same time the meanings of
"preferably greater than X" and "preferably smaller than Y".
[0020] The reflective film according to the present embodiment
(hereinafter referred to as "the present reflective film") is an
aliphatic polyester series film provided with a resin layer A
formed from a resin composition A containing an aliphatic polyester
series resin, a thermoplastic resin incompatible with the aliphatic
polyester series resin (hereinafter also referred to as
"incompatible resin"), a compatibilizing agent and a fine powder
filler.
Resin Layer A
[0021] The resin layer A can be formed from a resin composition A
containing an aliphatic polyester series resin, a thermoplastic
resin incompatible with the aliphatic polyester series resin
(hereinafter also referred to as "incompatible resin), a
compatibilizing agent and a fine powder filler.
(Base Resin of Resin Layer A)
[0022] As aliphatic polyester series resins serving as a base resin
of resin layer A (resin serving as the main constituent of resin
layer A), those that have been chemically synthesized, those that
have been fermentation-synthesized by a microorganism, and mixtures
thereof, can be used.
[0023] As chemically synthesized aliphatic polyester series resins,
aliphatic polyester series resins obtained by ring-opening
polymerization of a lactone, such as poly .epsilon.-caprolactone,
aliphatic polyester series resins obtained by polymerization of a
dibasic acid and a diol, such as polyethylene adipate, polyethylene
azerate, polyethylene succinate, polybutylene adipate, polybutylene
azerate, polybutylene succinate, polybutylene succinate adipate,
polytetramethylene succinate and cyclohexane dicarboxylic
acid/cyclohexane dimethanol condensate, aliphatic polyester series
resins obtained by polymerization of a hydroxy carboxylic acid,
such as polylactic acid and polyglycol, aliphatic polyester series
resins in which a portion of ester bonds in the aliphatic polyester
series resin, for instance, 50% or less of the total ester bonds,
has been replaced by amide bonds, ether bonds, urethane bonds and
the like, and so on, can be cited.
[0024] In addition, as aliphatic polyester series resins
fermentation-synthesized by a microorganism, polyhydroxybutyrate,
copolymer of hydroxybutyrate and hydroxyvalerate, and the like, can
be cited.
[0025] It is desirable that the aliphatic polyester series resin
used in resin layer A is an aliphatic polyester series resin that
does not contain an aromatic ring. If an aliphatic polyester series
resin not containing an aromatic ring in the molecular chain, then
no ultraviolet light absorption occurs and the film does not
deteriorate or yellow by being exposed to ultraviolet light or by
receiving ultraviolet light emitted from a light source such as a
liquid crystal display device, which can prevent the light
reflectivity of the film from decreasing over time.
[0026] In the resin layer A, light reflectivity can be obtained by
the refractive scatter at the interface between the base resin and
the fine powder filler or the like. Since this refractive scatter
becomes larger as the difference in the refractive index between
the base resin the fine powder filler becomes larger, it is
desirable to use a resin with a small refractive index as the base
resin so that the refractive index difference with the fine powder
filler becomes large.
[0027] From such point of view, among the aliphatic polyester
series resins mentioned above, it is desirable to use an aliphatic
polyester series resin with a refractive index of less than 1.52,
and in particular, it is more desirable to use a lactic acid series
polymer, which has a small refractive index among aliphatic
polyester series resins (refractive index of less than 1.46). In
addition, since lactic acid series polymers do not contain an
aromatic ring in the molecular chain, they do not give rise to
ultraviolet light absorption. Therefore, they are also desirable
from point that the reflective film does not deteriorate or yellow,
even if exposed to ultraviolet light, or by an ultraviolet light
emitted from a light source such as a liquid crystal display
device.
[0028] Lactic acid series polymer refers to a polymer of D-lactic
acid or L-lactic acid alone, or a copolymer thereof. Concretely,
there are poly(D-lactic acid) in which the structural unit is
D-lactic acid, poly(L-lactic acid) in which the structural unit is
L-lactic acid, and furthermore, poly(DL-lactic acid), which is a
copolymer of L-lactic acid and D-lactic acid, and in addition,
mixtures thereof are also included.
[0029] Lactic acid series polymers can be manufactured by well
known methods, such as condensation polymerization method and
ring-opening polymerization method. For instance, with the
condensation polymerization method, a lactic acid series polymer
having an arbitrary composition can be obtained by direct
dehydration condensation polymerization of D-lactic acid, L-lactic
acid or a mixture thereof. In addition, with the ring-opening
polymerization method, a lactic acid series polymer having an
arbitrary composition can be obtained by ring-opening
polymerization of a lactide, which is a cyclic dimer of lactic
acid, as necessary while using a polymerization adjuster or the
like and in the presence of a given catalyst. The above lactide
comprises L-lactide, which is a dimer of L-lactic acid, D-lactide,
which is a dimer of D-lactic acid and DL-lactide, which is a dimer
of D-lactic acid and L-lactic acid; these are mixed as necessary
and polymerized to allow a lactic acid series polymer having an
arbitrary composition and crystallinity to be obtained.
[0030] Among the lactic acid series polymers described above, those
in which the proportion of the contents in D-lactic acid and
L-lactic acid is D-lactic acid:L-lactic acid=100:0 to 85:15 or
D-lactic acid:L-lactic acid=0:100 to 15:85 are desirable, among
which in particular those with D-lactic acid:L-lactic acid=99.5 0.5
to 95:5 or D-lactic acid:L-lactic acid=0.5:99.5 to 5:95 are
desirable.
[0031] Lactic acid series polymers in which the proportion of the
contents in D-lactic acid and L-lactic acid is 100:0 or 0:100
demonstrate extremely high crystallinity, have a high melting
point, and tend to have excellent heat resistance and mechanical
physical properties. That is to say, when a film is stretched or
heat-treated, the resin crystallizes, improving heat resistance and
mechanical physical properties, such that they are desirable on
this point. Meanwhile, lactic acid series polymers constituted by
D-lactic acid and L-lactic acid are conferred flexibility,
improving film forming stability and stretching stability, thus
they are desirable on this point.
[0032] When the balance between heat resistance and forming
stability and stretching stability of the obtained reflective film
is considered, as lactic acid series polymers used in the resin
layer A, it is more desirable that the constitution ratio between
D-lactic acid and L-lactic acid is D-lactic acid:L-lactic
acid=99.5:0.5 to 95:5 or D-lactic acid:L-lactic acid=0.5:99.5 to
5:95.
[0033] A plurality of species of lactic acid series polymers with
different proportions of contents in D-lactic acid and L-lactic
acid may be mixed (blended). For instance, difficulty in bleeding
and expression of heat resistance can be balanced by blending a
homopolymer of D-lactic acid or L-lactic acid and a copolymer
thereof.
[0034] When mixing a plurality of species of lactic acid series
polymers in this way, it suffices that the value averaging the
proportions of contents in D-lactic acid and L-lactic acid from a
plurality of lactic acid series polymers falls within the range
mentioned above.
[0035] It is desirable that the molecular weight of the lactic acid
series polymer is a high molecular weight. For instance, it is
desirable that the weight average molecular weight is 50,000 or
greater, 60,000 to 400,000 being more desirable and 100,000 to
300,000 being particularly desirable. If the weight average
molecular weight of lactic acid series polymer is less than 50,000,
the obtained film sometimes has poor mechanical strength.
[0036] Commercial products can be also used as the aliphatic
polyester series resin. For instance, Bionolle 3000 series
manufactured by SHOWA HIGHPOLYMER CO., LTD., GS-Pla manufactured by
Mitsubishi Chemical Corporation and the like, can be cited. In
addition, Lacea series manufactured by Mitsui Chemicals, Inc.,
NatureWorks series manufactured by NatureWorks LLC and the like,
can be cited as lactic acid series polymers.
(Incompatible Resin)
[0037] As thermoplastic resin incompatible with aliphatic polyester
series resin (incompatible resin), polycarbonate series resin,
polystyrene series resin, acrylic series resin, polyolefin series
resin, and the like, may be cited, among which polyolefin series
resin is desirable.
[0038] Here, thermoplastic resin incompatible with aliphatic
polyester series resin (incompatible resin) refers to a
thermoplastic resin, which, when mixed with an aliphatic polyester
series resin, demonstrates a state that is not blended (separated
state) in the nanometer order (at the molecule level).
[0039] Whether or not the resins are incompatible can be assessed
if, when the glass transition temperature (hereinafter also
referred to as "Tg") of the polymer blend obtained by mixing is
measured, not a single Tg but the Tgs of the respective resins
appear. More specifically, the resins can be assessed to be
incompatible if there are two or more main dispersion peaks for the
loss elastic modulus or if there are two or more maximum values for
the loss tangent (tan .delta.), as measured by the temperature
dispersion measurement of dynamic viscoelasticity at 0.1%
distortion, 10 Hz frequency and 3.degree. C./minute temperature
rise rate (dynamic viscoelasticity measurement in JIS K-7198, A
method), and further in addition, if two or more inflexion points,
which indicate glass transition temperatures, appear when glass
transition temperature is measured according to JIS K7121 at
10.degree. C./minute heating rate using a differential scanning
calorimeter.
[0040] Among the polyolefin series resins, monoolefin polymers such
as, for instance, polyethylene and polypropylene, or copolymers
thereof, and the like, are desirable.
[0041] Concretely, polyethylene series resins such as low density
polyethylene, linear low density polyethylene (for instance
ethylene-.alpha.-olefin copolymer), medium density polyethylene and
high density polyethylene, polybutylene series resins,
polypropylene series resins such as polypropylene and
ethylene-propylene copolymer, poly 4-methylpentene, polybutene,
ethylene-vinyl acetate copolymer, and the like, can be cited. These
resins may be used alone or by mixing two or more species.
[0042] Polyolefin series resins include those manufactured using a
multi-site catalyst such as a Ziegler catalyst and those
manufactured using a single site catalyst such as a metallocene
catalyst.
[0043] In addition, polyolefin series thermoplastic elastomers
comprising ethylene-propylene rubber or the like dispersed in and
conjugated with these polyolefin series resins can be also
used.
[0044] If formability when being formed into sheet-shape, as well
as heat resistance after being formed into sheet-shape, and the
like, are taken into account, among the polyolefin series resin
described above, linear low density polyethylene resins such as
ethylene-.alpha.-olefin copolymer, polypropylene series resins such
as polypropylene, ethylene-propylene copolymer, propylene-butene
copolymer, ethylene-propylene-butene terpolymer and
ethylene-propylene-diene terpolymer, and the like, are desirable,
among which polypropylene series resins, and particularly
polypropylene and ethylene-propylene copolymer such as
ethylene-propylene random copolymer, are desirable.
[0045] In addition, from the point of view of reflectance
improvement, a polyolefin with a small refractive index is
preferred; the use of a polyolefin series resin with a refractive
index of less than 1.52 being particularly desirable. For instance,
polypropylene series resins, low density polyethylene series
resins, polybutylene series resins, polymethylpentene and mixtures
and copolymers thereof, and the like, can be cited; among them,
polypropylene series resins with a refractive index of greater than
1.50 are desirable.
[0046] As polypropylene series resins, homopolypropylene resins,
random polypropylene resins, block polypropylene resins,
propylene-ethylene rubber, and the like, can be cited.
[0047] As polymerization methods for obtaining a polypropylene
series resin, well known methods can be adopted such as, for
instance, solvent polymerization method, bulk polymerization method
and gas phase polymerization method. In addition, as polymerization
catalysts, well known catalyst can be adopted, such as, for
instance, titanium trichloride-type catalyst, magnesium
chloride-supported catalyst and metallocene series catalyst.
[0048] Although the melt flow rate (MFR) of polyolefin series resin
is not limited in particular, if dispersability into the base resin
is taken into consideration, it is desirable that the MFR
(temperature: 190.degree. C.; load: 2.16 kg) is, in the case of a
polyethylene series resin, on the order of 0.2 to 40 g/10 min
(190.degree. C.; load: 2.16 kg), in particular 1 to 20 g/10 min,
among which in particular 3 to 10 g/10 min. In the case of a
polypropylene series resin, 1 to 50 g/10 min (230.degree. C.; load:
2.16 kg), in particular 3 to 25 g/10 min, among which particularly
5 to 15 g/10 min is desirable.
[0049] Note that, in the present invention, MFR is the one measured
based on the methods specified in ASTMD-1238. However, the
measurements are meant to be measured under each condition
indicated in parentheses.
[0050] If the MFR of the polyolefin series resin is too small, the
extrusion temperature needs to be increased at melt-forming, which
can result in yellowing due to heat deterioration of the aliphatic
polyester series resin or the polyolefin series resin per se, or a
decrease in reflectance due to heat deterioration of the fine
particle filler, in particular of titanium oxide. Meanwhile, if the
MFR of the polyolefin series resin is too large, there is the
possibility that sheet fabrication by melt-forming becomes
unstable.
[0051] When light reflectivity, elastic modulus, film-forming
ability, and the like, of the film are considered, the proportion
of the content in incompatible resin with respect to the total mass
of resin layer A is preferably 1 to 30 percent in mass and more
preferably 3 to 20 percent in mass. If the proportion of the
content in incompatible resin is 1 percent in mass or greater, it
is desirable since a high light reflectivity and suppression of
elastic modulus of the film can be realized simultaneously. In
addition, if the proportion of the content in incompatible resin is
30 percent in mass or less, the film-forming ability of the film
can be secured.
(Compatibilizing Agent)
[0052] In the present reflective film, a compatibilizing agent
means a compound allowing the dispersability of an incompatible
resin with respect to an aliphatic polyester series resin to be
increased, by adding such a compatibilizing agent, the size of the
disperse phase comprising the incompatible resin can be controlled
to a suitable extent.
[0053] As compatibilizing agents used in the present reflective
film, it is important to use SEBS
(styrene=ethylene=butylene=styrene) series compounds or glycidyl
metacrylate-ethylene series copolymers, or mixtures thereof. These
compatibilizing agents allow the dispersability of the incompatible
resin within the aliphatic polyester series resin to be increased
effectively. In particular, the dispersability of the incompatible
resin can be increased particularly effectively in aliphatic
polyester series resins that heat-melt at comparatively low
temperatures, such as lactic acid series polymers.
[0054] As SEBS series compounds, styrene-ethylene/butylene-styrene
block copolymers, hydrogenated-styrene-ethylene/butylene-styrene
block copolymers, and furthermore,
styrene-ethylene/butylene-styrene block copolymers of the type
introduced with a functional group may be cited. In the
styrene-ethylene/butylene-styrene block copolymers of the type
introduced with a functional group, as the functional groups to be
introduced, for instance, acetoxy group, carboxyl group, hydroxyl
group, dihydroxyl group, metacryloyl group, epoxy group, and
furthermore, glycidyl metacrylate group having an epoxy group, or
maleic anhydride constituent, butadiene component, styrene series,
acryl series, vinyl series monomer and polymer of the
acrylonitrile-styrene series, and the like, may be cited. These
functional groups can be introduced alone or by combining two or
more species. Among them, styrene-ethylene/butylene-styrene block
copolymers of the type introduced with a butadiene component and
styrene-ethylene/butylene-styrene block copolymers of the type
introduced with a glycidyl metacrylate group are particularly
desirable.
[0055] As glycidyl metacrylate-ethylene series copolymers, for
instance, copolymers and terpolymers comprising glycidyl
metacrylate, containing at least an epoxy group, and ethylene may
be cited.
[0056] Here, as the terpolymer, for instance, terpolymers of epoxy
group-containing glycidyl metacrylate, ethylene and vinyl acetate
or methyl acrylate, or the like, may be cited. Among them, a
terpolymer comprising epoxy group-containing glycidyl metacrylate,
ethylene and methyl acrylate is desirable.
[0057] When light reflectivity, mechanical physical properties,
film-forming ability, and the like, of the film are considered, the
proportion of the content in compatibilizing agent with respect to
the total mass of the resin layer A is preferably 0.1 to 7 percent
in mass and more preferably 1 to 5 percent in mass.
[0058] If the proportion of the content in compatibilizing agent is
0.1 percent in mass or greater, it is effective for controlling the
size of the dispersed phase of the incompatible resin to a suitable
extent and desirable for suppressing the occurrence of die drool
(lump from attachment and deposition on the port lip of an
extruder, a T-die and the like) and pimply skin (microscopic film
defect) at film-forming and for preventing rupture during
stretching. In addition, if the proportion of the content in
compatibilizing agent is 7 percent in mass or lower, excellent
light reflectivity can be conferred to the film. In addition, it is
desirable as no detrimental effect is exerted throughout the whole
extrusion and film-forming processes.
(Fine Powder Filler)
[0059] As fine powders used in resin layer A, organic fine powder,
mineral fine powder, and the like, can be cited.
[0060] As organic fine powder, at least one species chosen from
cellulose series powders such as wood powder and pulp powder,
polymer beads, polymer hollow particles, and the like, can be
cited.
[0061] As mineral fine powder, at least one species chosen from
calcium carbonate, magnesium carbonate, barium carbonate, magnesium
sulfate, barium sulfate, calcium sulfate, zinc oxide, magnesium
oxide, calcium oxide, titanium oxide, alumina, aluminum hydroxide,
hydroxyapatite, silica, mica, talc, kaolin, clay, glass powder,
asbestos powder, zeolite, soft silica, and the like, can be cited,
among which, one species, or, a mixture comprising a combination of
two or more species, chosen from the group of calcium carbonate,
zinc oxide, barium sulfate and titanium oxide, is desirable.
[0062] When light reflectivity of the obtained reflective film is
considered, those with a large refractive index difference with the
base resin is desirable. That is to say, as mineral fine powders,
those with a large refractive index, those with 1.6 or greater as a
criteria, are desirable. Concretely, it is desirable to use calcium
carbonate, barium sulfate, zinc oxide or titanium oxide, which
refractive indices are 1.6 or greater, among which titanium oxide,
which has a high refractive index, is particularly desirable.
However, when long-term durability is considered, barium sulfate,
which is stable against acids and alkali, is also particularly
desirable.
[0063] Note that mineral fine powders and organic fine powders, as
shown above as examples, may be used in combination as a fine
powder filler. In addition, different fine powder fillers can be
used concomitantly; for instance, titanium oxide and another fine
powder filler may be used concomitantly.
[0064] Since titanium oxide has a refractive index that is
remarkably high compared to other mineral fine powders, allowing
the refractive index difference with the base resin to be
remarkably large, excellent reflectivity can be obtained with less
mixing amount than when another filler is used. In addition, using
titanium oxide allows a reflective film having high reflectivity to
be obtained even if the thickness of the film is thin.
[0065] Consequently, it is desirable to use a fine powder filler
containing at least titanium oxide, in which case the amount of
titanium oxide is preferably 30% or greater of the total mass of
the fine powder filler.
[0066] As titanium oxides used in resin layer A, titanium oxides of
the crystal-type, such as anatase-type and rutile-type are
desirable, among which, from the point of view of a large
refractive index difference with the base resin, titanium oxide
with a refractive index of 2.7 or greater is desirable. On this
point, the rutile-type titanium oxide is desirable.
[0067] In addition, among the titanium oxides, it is particularly
desirable to use a high purity titanium oxide with a high purity.
Here, high purity titanium oxide means titanium oxide with a small
light absorption capability with respect to visible light, that is
to say, titanium oxide in which the contents in colored elements
such as vanadium, iron, niobium, copper and manganese are small; in
the present invention, a titanium oxide in which the niobium
content is 500 ppm or less and the vanadium content is 5 ppm or
less is designated as high purity titanium oxide.
[0068] In a high purity titanium oxide, it is important that the
niobium content is 500 ppm or less, and preferably 400 ppm or less.
In addition, it is important that the vanadium content is 5 ppm or
less, and preferably 4 ppm or less.
[0069] As high purity titanium oxides, for instance, those
manufactured by the chlorine method process can be cited.
[0070] In the chlorine method process, high purity titanium oxide
can be obtained by reacting rutile ore, which has titanium oxide as
the main constituent, with chlorine gas in a high temperature oven
at on the order of 1000.degree. C. to generate titanium
tetrachloride first and then by burning this titanium tetrachloride
with oxygen.
[0071] As industrial manufacturing method of titanium oxide, there
is also the sulfuric acid method process; however, in the titanium
oxide obtained by this method, colored elements such as vanadium,
iron, copper, manganese and niobium are contained in large
quantities, such that the light absorption capability with respect
to visible light becomes large. Consequently, high purity titanium
oxide is difficult to obtain by the sulfuric acid method
process.
[0072] As fine powder fillers, in particular titanium oxides, those
provided on the surface with an inert organic oxide layer formed
from an inert organic oxide are desirable. By cover treatment of
the surface of titanium oxide with an inert organic oxide, the
photocatalytic activity of titanium oxide can be suppressed,
allowing deterioration of the film due to photocatalytic action of
titanium oxide to be prevented.
[0073] As inert organic oxide, it is desirable to use at least one
species chosen from the group comprising silica, alumina and
zirconia. If these inert organic oxides are used, light resistance
of the film can be raised without impairing the high light
reflectivity exerted when titanium oxide is used. In addition, it
is more desirable to use two or more species of inert organic
oxides concomitantly, among which combinations in which silica is
essential are particularly desirable.
[0074] It is desirable that the inert organic oxide layer occupies
0.5 to 7 percent in mass of the total mass of titanium oxide, and
in particular 1 to 3 percent in mass. If the inert organic oxide
layer is 0.5 percent in mass or greater, it is desirable since
maintaining high reflectivity is facilitated. In addition, if the
inert organic oxide layer is 7 percent in mass or lower, it is
desirable since dispersability into polyester series resin becomes
satisfactory allowing a homogeneous film to be obtained.
[0075] Note that the proportion occupied by the inert organic oxide
layer in the total mass of titanium oxide can be determined by the
proportion (represented by a percentage) of the total mass of inert
organic oxide used in the surface treatment occupied within the
total mass of titanium oxide after surface treatment.
[0076] In addition, it is desirable that the mineral fine powder,
and in particular titanium oxide, is provided on the surface with
an organic compound layer formed from an organic compound, in order
to increase dispersability into base resin.
[0077] The organic compound layer can be formed by cover treatment
of the surface of titanium oxide or the surface of the inert
organic oxide layer described above with organic compounds such as,
for instance, siloxane compound, silane coupling agent, multivalent
alcohol, titanium coupling agent, alkanolamine or derivatives
thereof, and higher fatty acid or metal salts thereof, and the
like. In particular, cover treatment with at least one species of
organic compound chosen from the group comprising siloxane
compound, multivalent alcohol, and silane coupling agent is
desirable, among which in particular, cover treatment with at least
one species of organic compound chosen from the group comprising
multivalent alcohol and silane coupling agent is desirable. These
two species or more compounds may be combined and used.
[0078] By physically adsorbing or chemically reacting with hydroxyl
groups on the surface of titanium oxide, these organic compounds
can improve the hydrophobicity, dispersability and affinity with
the resin, of the titanium oxide.
[0079] Here, as the siloxane compounds described above, for
instance, dimethyl silicone, methyl hydrogen silicone,
alkyl-modified silicone, and the like, can be cited; these can be
used alone or by combining two or more species.
[0080] As the silane coupling agents described above, for instance,
alkoxy silanes having an alkyl group, an alkenyl group, an amino
group, an aryl group, an epoxy group, and the like, chlorosilanes
and polyalkoxyalkyl siloxanes are desirable, and aminosilane
coupling agents are more desirable. Concretely, for instance,
aminosilane coupling agents, such as
n-.beta.(aminoethyl).gamma.-aminopropylmethyldimethoxy silane,
n-.beta.(aminoethyl).gamma.-aminopropylmethyltrimethoxy silane,
n-.beta.(aminoethyl).gamma.-aminopropylmethyltriethoxy silane,
.gamma.-aminopropyltriethoxy silane, .gamma.-aminopropyltrimethoxy
silane and n-phenyl-.gamma.-aminopropyltrimethoxy silane, and alkyl
silane coupling agents, such as dimethyldimethoxy silane,
methyltrimethoxy silane, ethyltrimethoxy silane, propyltrimethoxy
silane, n-butyltrimethoxy silane, n-butyltriethoxy silane,
n-butylmethyldimethoxy silane, n-butylmethyldiethoxy silane,
isobutyltrimethoxy silane, isobutyltriethoxy silane,
isobutylmethyldimethoxy silane, tert-butyltrimethoxy silane,
tert-butyltriethoxy silane, tert-butylmethyldimethoxy silane and
tert-butylmethyldiethoxy silane, can be cited; these can be used
alone or by combining two or more species.
[0081] As the multivalent alcohols described above, for instance,
trimethylol ethane, trimethylol propane, tripropanol ethane,
pentaerythritol, and pentaerythrit, and the like, can be cited,
among which trimethylol ethane and trimethylol propane are more
desirable. Regarding these multivalent alcohol compounds, these can
be used alone or by combining two or more species.
[0082] It is desirable that the organic compound layer occupies
0.01 to 5 percent in mass of the total mass of titanium oxide, in
particular 0.05 to 3 percent in mass, among which in particular 0.1
to 2 percent in mass.
[0083] If the organic compound layer occupies 0.01 percent in mass
or greater of the entirety of the titanium oxide, moisture
adsorption by the titanium oxide can be prevented and the
aggregation of titanium oxide particles can be prevented,
therefore, the dispersability of the titanium oxide can be
increased. If the dispersability of the titanium oxide is
increased, the surface area of the interface between the base resin
and titanium oxide is secured thoroughly, therefore, a high light
reflectivity can be conferred to the film. Meanwhile, if the
organic compound layer is 5 percent in mass or lower of the
entirety of the titanium oxide, the lubricity of titanium oxide
particle becomes suitable, which enables stable extrusion and
film-forming.
[0084] The proportion occupied by the organic compound layer in the
total mass of titanium oxide can be determined by the proportion
(represented by a percentage) of the total mass of organic compound
used in the surface treatment occupied within the total mass of
titanium oxide after surface treatment.
[0085] When a fine powder filler other than titanium oxide is used,
in order to increase dispersability into the base resin, it is
desirable for this fine powder filler to use one for which a
surface treatment has been performed on the surface of the fine
powder filler with a silicon series compound, a multivalent alcohol
series compound, an amine series compound, a fatty acid, a fatty
acid ester, or the like.
[0086] The particle diameter of the fine powder filler is
preferably 0.05 .mu.m to 15 .mu.m, more preferably 0.1 .mu.m to 10
.mu.m, among which 0.3 .mu.m to 10 .mu.m is more desirable. If the
particle diameter of the fine powder filler is 0.05 .mu.m or
greater, dispersability into the base resin is satisfactory,
allowing a homogeneous film to be obtained. In addition, if 0.3
.mu.m or greater, light scatter reflection is generated
concomitantly to surface roughening of the film, such that
reflection directionality of the obtained film becomes small, which
is desirable. In addition, if the particle diameter is 15 .mu.m or
less, the interface between the base resin and the fine powder
filler is formed tightly, allowing a film with high reflectivity to
be obtained.
[0087] When titanium oxide is used as fine powder filler, it is
desirable that the particle diameter thereof is 0.1 .mu.m to 1.0
.mu.m, and 0.2 .mu.m to 0.5 .mu.m is more desirable. If the
particle diameter of titanium oxide is 0.1 .mu.m or greater,
dispersability into the base resin is satisfactory, allowing a
homogeneous film to be obtained. In addition, if the particle
diameter of titanium oxide is 1.0 .mu.m or less, the interface
between the base resin and titanium oxide is formed tightly,
allowing high light reflectivity to be provided to the reflective
film.
[0088] When light reflectivity, mechanical physical properties,
film-forming ability, and the like, of the film are considered, the
content in fine powder filler with respect to the mass of the
entirety of the resin layer A is preferably 10 to 50 percent in
mass and more preferably 20 to 40 percent in mass.
[0089] If the content in fine powder filler is 10 percent in mass
or greater, the surface area of the interface between the base
resin and fine powder filler can be secured thoroughly, therefore,
a high light reflectivity can be conferred to the film. In
addition, if the content in fine powder filler is 50 percent in
mass or lower, mechanical strength and film-forming ability
necessary to the film can be secured.
(Other Constituents)
[0090] To the extent that the effects of aliphatic polyester series
resin, incompatible resin, compatibilizing agent and fine powder
filler are not impeded, the resin layer A may contain a resin other
than these (referred to as "other constituent resin"). In addition,
to the extent that the effects described above are not impeded, an
oxidation inhibitor, a light stabilizer, a heat stabilizer, a
dispersant, an ultraviolet light absorbent, a fluorescent whitener,
and other additives may be contained.
[0091] As other constituent resins described above, for instance,
when a lactic acid series polymer, or the like, is used as a base
resin, addition of a carbodiimide compound, which is an
anti-hydrolysis agent, or the like, can be considered for the
purpose of conferring durability against an environment with higher
temperature and high humidity. Particularly, since liquid crystal
displays in recent years are used in car navigation systems for
automobiles, small on-board televisions, and the like, in addition
to displays for personal computers, rendering necessary those
displays that resist high temperature and high humidity, it is
desirable to add an anti-hydrolysis agent for the purpose of
conferring durability.
[0092] As carbodiimide compounds, for instance, those having the
fundamental structure of the following General Formula (1) may be
given as desirable ones:
--(N.dbd.C.dbd.N--R--)n- (1)
[0093] In the formula, n represents the integer 1 or greater and R
represents an organic series bond unit. For instance, R can be any
of aliphatic, alicyclic and aromatic. In addition, for n, in
general, an appropriate integer is selected between 1 to 50.
[0094] Concretely, for instance, bis(dipropyl phenyl) carbodiimide,
poly(4,4'-diphenylmethane carbodiimide), poly(p-phenylene
carbodiimide), poly(m-phenylene carbodiimide), poly(tolyl
carbodiimide), poly(diisopropyl phenylene carbodiimide),
poly(methyl-diisopropyl phenylene carbodiimide), poly(triisopropyl
phenylene carbodiimide) and the like, and monomers thereof, may be
cited as carbodiimide compounds. These carbodiimide compounds may
be used alone or may be used by combining two or more species.
[0095] It is desirable that the amount of carbodiimide compound
added is 0.1 to 3.0 parts in mass with respect to 100 parts in mass
of aliphatic polyester series resin. If the amount of carbodiimide
compound added is 0.1 parts in mass or greater, the effects of
improving the resistance to hydrolysis can be expressed
sufficiently. In addition, if the amount of carbodiimide compound
added is 3.0 parts in mass or less, there is little coloration of
the obtained film and light reflectivity is not impaired.
(Porosity)
[0096] In order to obtain higher reflection capabilities, and
furthermore, in order to obtain a more satisfactory
fold-processability, it is desirable to have voids inside the resin
layer A. If there are voids inside the resin layer A, in addition
to the refractive scatter due to the refractive index difference
between aliphatic polyester series resin and fine powder filler and
the refractive scatter due to the refractive index difference
between incompatible resin and fine powder filler, reflectivity can
be obtained also from the refractive scatter due to the refractive
index difference between aliphatic polyester series resin and void
(air), incompatible resin and void (air), and fine powder filler
and void (air).
[0097] In addition, it is also desirable to have voids inside the
resin layer A, in order to confer a satisfactory
fold-processability to the film. If there are voids inside the
resin layer A, the elastic modulus of the film (dynamic storage
modulus) decreases, allowing fold-processability of the film to be
improved. For instance, in case a reflective plate formed by
layering the film over a metal plate is fold-processed, since no
strain remains in the reflective plate at fold-processing owing to
the dynamic storage modulus of the film being adjusted to be low,
the dimensions of the reflective plate become resistant to change
during use.
[0098] Note that this effect of fold-processability improvement is
also assumed to be generated by the voids formed at the folding
sites of the film absorbing the folding deformation.
[0099] A porosity of the resin layer A, that is to say, the
proportion occupied inside the resin layer A by the volume portion
of the void, of 30 to 60%, of which, from the point of view of
reflectance improvement and fold-processability improvement, 35% or
greater, is desirable. If porosity of the resin layer A is 30% or
greater, reflection capability and fold-processability can be
raised sufficiently; in addition, if porosity is 60% or lower, the
mechanical strength and film-forming ability of the film are
maintained, preventing rupture of film during film fabrication and
insufficient durability such as heat resistance during use. Note
that the porosity when the film is stretched can be calculated by
the following formula.
Porosity (%)={(film density before stretching-film density after
stretching)/film density before stretching}.times.100
[0100] Voids in resin layer A can be formed for instance by melting
the resin composition A, film-forming and stretching the obtained
film. This is due to a difference in the stretching behavior
between the base resin and the fine powder filler and incompatible
resin when stretched. That is to say, if stretching is conducted at
a stretching temperature that is suited to the base resin, the base
resin serving as the matrix is stretched while the fine powder
filler and the incompatible resin tend to remain in an as-is state,
such that the base resin and the fine powder filler detach at the
interface, forming voids as well as the base resin and the
incompatible resin. Consequently, the porosity of resin layer A can
be controlled by adjusting the species and amounts of the fine
powder filler and incompatible resin, as well as the stretch ratio
and the like.
[0101] In addition, since voids can be also formed inside the resin
layer A by adding a foaming agent into the resin composition A to
foam, in this case, the porosity of resin layer A can be controlled
by adjusting the species and amount of the foaming agent.
[0102] In the resin layer A, a disperse phase comprising the
incompatible resin is in a disseminated state in the mother phase
(matrix) comprising the base resin; in so doing, it is desirable
that the mean diameter of the disperse phase is in the range of 0.1
.mu.m to 5 .mu.m, and in particular, a range of 0.5 .mu.m to 3
.mu.m is more desirable. If the size of the disperse phase is 0.1
.mu.m or greater, the size of the void formed by stretching becomes
one that is sufficient for reflecting light in the visible light
region. In addition, if the size of the disperse phase is 5 .mu.m
or less, the surface area of the interface between the void formed
by stretching and the base resin can be maintained thoroughly such
that high light reflectivity can be conferred to the film, which is
desirable. In addition, if the size of the disperse phase is 5
.mu.m or less, it is desirable since the bubbles formed in the
periphery thereof become compact, improving mechanical strength
along with stretch film-forming ability.
[0103] The size of the disperse phase can be controlled by the
species and amount of compatibilizing agent, in addition, it can be
also controlled by adjusting the extrusion temperature of the
extruder and screw rotation speed of the extruder when the resin
composition undergoes melting and film-forming.
(Morphology of Resin Layer A)
[0104] The resin layer A may be a layer comprising a film or may be
a layer comprising a molten resin composition formed into a thin
film by extrusion or coating or the like (without forming a film).
In addition, if comprising a film, although this film may be a
non-stretched film or a uniaxially or biaxially stretched film, a
stretched film obtained by stretching 1.1-fold or more in at least
one axial direction, and particularly a biaxially stretched film
are desirable.
[Layered Constitution of the Present Reflective Film]
[0105] As the layered constitution of the present reflective film,
since the provision of a resin layer A suffices, [the film] may be
a monolayer film comprising only a resin layer A; in addition, the
film may be a layered film provided with a constitution comprising
layering a layer other than the resin layer A.
[0106] As layered film, for instance, a two-layer layered
constitution provided with a resin layer A and a resin layer B
containing an aliphatic polyester series resin and a fine powder
filler can be cited. In this case, although layering in the resin
layer A/resin layer B and resin layer B/resin layer A orders from
the side where irradiated by light (side of the surface for
reflection use) can be considered, layering in the resin layer
B/resin layer A order from the side where irradiated by light (side
of the surface for reflection use) is desirable.
[0107] In addition, a layer other than resin layer A and resin
layer B may be provided, and another layer may be intercalated
between each of the resin layer A and the resin layer B. For
instance, an adhesive layer may be intercalated between the resin
layer A and the resin layer B.
Resin Layer B
[0108] The resin layer B described above can be formed from a resin
composition B containing an aliphatic polyester series resin and a
fine powder filler, and containing no incompatible resin and
compatibilizing agent.
[0109] Reflection capability of the present reflective film can be
increased further by layering such a resin layer B with the resin
layer A.
[0110] The aliphatic polyester series resins that can be used for
the resin layer B are the same as the aliphatic polyester series
resins that can be used for the resin layer A, and the preferred
species are the same as well.
[0111] In addition, the fine powder fillers that can be used for
the resin layer B are the same as the fine powder filler that can
be used for the resin layer A. For instance, as fine powder
fillers, one species or a mixture comprising a combination of two
or more species chosen from the group of calcium carbonate, zinc
oxide, barium sulfate and titanium oxide, can be cited. The
preferable species of fine powder filler are the same as the fine
powder fillers of the resin layer A.
[0112] Note that, barium sulfate, which is stable against acids and
alkali, is desirable from the point of view of durability of the
film, and silica and titanium oxide are desirable from the point of
view of appearance of the film.
[0113] When light reflectivity, mechanical physical properties,
film-forming ability, and the like, of the film are considered, the
content in fine powder filler in the resin layer B with respect to
the mass of the entirety of resin layer B is preferably 0.1 to 5
percent in mass; 0.1 to 3 percent in mass and among this 0.1 to 1
percent in mass being more desirable.
[0114] When integrating the reflective film into a liquid crystal
display device, or the like, if the content in fine powder filler
in the B layer becomes greater than 5 percent in mass, a tendency
for the brightness to decrease notably is observed. The reason for
this is thought to be due to the interface between the base resin
and the fine particle filler becoming detached to form voids inside
the B layer when the B layer is stretched 1.1-fold or more in at
least one axial direction, lowering the degree of brilliance.
[0115] In addition, when a B layer is provided as the outermost
layer of the reflective film, if no fine powder filler is contained
in the outermost layer, the film surface being too flat, films rub
against each other during fabrication or during transport and the
like and are readily scratched due to a so-called roll slippage;
therefore, the amount of fine powder filler inside the resin layer
B is preferably 0.1 to 5 percent in mass, also from this point.
[0116] Further in addition, if no fine powder filler is contained
in the outermost layer, detachment occurs readily between the A
layer and the B layer, such that the amount of fine powder filler
inside the resin layer B is preferably 0.1 to 5 percent in mass,
also from this point.
(Other Constituents)
[0117] To the extent that the effects of aliphatic polyester series
resin and fine powder filler are not impeded, the resin layer B may
contain a resin other than the aliphatic polyester series resin
described above. In addition, to the extent that the effects
described above are not impeded, an anti-hydrolysis agent (for
instance described above carbodiimide), an oxidation inhibitor, a
light stabilizer, a heat stabilizer, a dispersant, an ultraviolet
light absorbent, a fluorescent whitener, and other additives may be
contained.
(Morphology of Resin Layer B)
[0118] The resin layer B may be a layer comprising a film or may be
a layer comprising a molten resin composition formed into a thin
film by extrusion or coating or the like (without forming a film).
In addition, if comprising a film, although this film may be a
non-stretched film or a uniaxially or biaxially stretched film, a
stretched film obtained by stretching 1.1-fold or more in at least
one axial direction, and particularly a biaxially stretched film
are desirable.
Thickness
[0119] Although the thickness of the present reflective film is not
limited in particular, it is preferably 30 .mu.m to 1500 .mu.m in
general, and preferably within a range on the order of 50 .mu.m to
1500 .mu.m when handling ability in practical aspects is
considered.
[0120] For instance, as a reflective film for a small and thin
reflective plate application, it is desirable that the thickness is
30 .mu.m to 200 .mu.m. If a reflective film with such a thickness
is used, it can be also used for instance in small and thin liquid
crystal displays, or the like, of notebook-type personal computers,
mobile phones, and the like.
[0121] Meanwhile, as reflective films and reflective plates of
large liquid crystal televisions, or the like, it is desirable that
the thickness is 75 .mu.m to 1500 .mu.m.
[0122] Note that, when providing a B layer, it is desirable that
the thickness ratio between the A layer and the B layer is 20:1 to
1:1, in particular 15:1 to 5:1, among which in particular 12:1 to
7:1. If the thickness ratio of the B layer is greater than when the
thickness ratio between the A layer and the B layer is 20:1, it is
desirable since the degree of brilliance becomes sufficient, which
facilitates obtaining satisfactory light reflection
characteristics. In addition, if the thickness ratio of the B layer
is smaller than when the thickness ratio between the A layer and
the B layer is 1:1, it is desirable since there is no detrimental
influence exerted on the reflection characteristics.
Dynamic Storage Modulus
[0123] As the elastic modulus of the present reflective film, it is
desirable the dynamic storage modulus of the film (E') is adjusted
in a range of 1.0 GPa to 3.0 GPa as measured at 10 Hz frequency and
23.degree. C. temperature by dynamic viscoelasticity measurement.
If the dynamic storage modulus of the film is 1.0 GPa or greater,
it is desirable on the point of handling ability since a suitable
extent of firmness is obtained in the film; 1.5 GPa or greater is
more desirable. In addition, if the dynamic storage modulus of film
is 3.0 Gpa or less, it is desirable on the point that a suitable
extent of flexibility is obtained in the film, which allows
fold-processability to be secured; 2.5 Gpa or less is more
desirable.
Reflectance
[0124] As the reflectance of the present reflective film, it is
desirable that the reflectance of the surface with respect to
lights of 700 nm and 550 nm wavelengths is 99.0% or greater as
measured from the side of the surface for reflection use. If the
reflectance is 99.0% or greater, the reflective film demonstrates
satisfactory reflection characteristics, and liquid crystal
displays, or the like, which have integrated this reflective film,
have satisfactory vividness without the screen thereof taking on a
yellow tinge.
Degree of Brilliance
[0125] In the present reflective film, the degree of brilliance,
when measured by irradiating light on the side of the surface for
reflection use and matching the incidence angle thereof and the
light receiving angle to 60.degree., is more preferably 50 to 95,
and particularly preferably 60 to 85.
[0126] Here, "degree of brilliance" is a quantity representing the
extent of reflection when light hits the surface of a reflective
film, a value indicated by a relative value with respect to a given
glass surface defined in JIS Z 8741 serving as a reference surface
and defining the degree of brilliance of this reference surface as
100.
[0127] Generally, if the degree of brilliance is high, normal
reflectivity becomes large and the surface appears glossy;
conversely, if the degree of brilliance is low, normal reflectivity
also becomes low, and the surface appears to be rough. Also in
reflective films, those with high normal reflectivity tend to have
high front brightness and satisfactory light reflection
capabilities. If the degree of brilliance on the side of the
surface for reflection use of the present reflective film at
60.degree. is in the range of 50 to 95, satisfactory light
reflection capabilities, and in particular satisfactory brightness,
are obtained. Such effects appear particularly notably in the case
of a constitution in which, sequentially from the liquid crystal
side in the internal constitution of a liquid crystal television, a
brightness improvement sheet, a diffusion sheet, a diffusion plate,
a cold cathode tube and a reflective film are layered. Conversely,
if the degree of brilliance is below 50, diffuse reflectivity
becomes high, decreasing front brightness. In addition, if the
degree of brilliance reaches above 95, when integrated into a
backlight, lines of cold cathode tube (emission line) are readily
seen, which is not desirable.
[0128] Note that, in the present reflective film, in order to set
the degree of brilliance to the given ranges described above, one
of the important conditions is to adjust the content in fine powder
filler in the B layer positioned at the outermost layer on the side
of the surface for reflection use, as described above.
Manufacturing Methods
[0129] In the following, a manufacturing method for the present
reflective film will be described giving one example; however, [the
manufacturing method for the present reflective film] is not to be
limited in any way by the manufacturing methods described
below.
[0130] First, a manufacturing method for a monolayer film
comprising only the resin layer A will be described; next a
manufacturing method for a bilayer film provided with a resin layer
A and a resin layer B will be described.
Manufacturing Method for a Monolayer Film
[0131] First, a fine powder filler, an incompatible resin, a
compatibilizing agent, and other additives, and the like, are mixed
as necessary with an aliphatic polyester series resin, to prepare
an aliphatic polyester series resin composition A. Concretely, the
resin composition A can be obtained by adding a fine powder filler,
an incompatible resin and a compatibilizing agent to an aliphatic
polyester series resin, as necessary further adding an additive
such as an oxidation inhibitor, mixing with a ribbon blender,
tumbler, Henschel mixer or the like, and then kneading at a
temperature equal to the melting point of the resin or higher using
a Banbury mixer, a uniaxial or biaxial extruder, or the like.
[0132] However, the resin composition A can be also obtained by
adding to the aliphatic polyester series resin, given amounts of
the fine powder filler, the incompatible resin, the compatibilizing
agent and the additives, or the like, with separate feeders or the
like. In addition, a so-called master batch can be manufactured,
comprising the fine powder filler, the incompatible resin, the
compatibilizing agent, the additives and the like, pre-mixed at
high concentrations in the aliphatic polyester series resin, and it
is also possible to obtain a resin composition A at the desired
concentration by mixing this master batch and the aliphatic
polyester series resin.
[0133] Next, the resin composition A obtained in this way is melted
and formed into a film-shape. For instance, the aliphatic polyester
series resin composition A is supplied to an extruder and heated
and melted at a temperature equal to or higher than the melting
point of the resin. Although it is necessary to consider the
decrease in molecular weight due to decomposition and the like to
set conditions such as the extrusion temperature, for instance, in
the case of a lactic acid series polymer, it is desirable that the
extrusion temperature is in the range of 170.degree. C. to
230.degree. C. Thereafter, the molten aliphatic polyester series
resin composition is extruded from a slit-shaped discharge port of
a T die, brought in firm contact with a cooling roll and solidified
to form a cast sheet.
[0134] In so doing, the size of the disperse phase can be
controlled by adjusting the extrusion temperature of the extruder
and the screw rotation speed of the extruder.
[0135] It is desirable that the obtained cast sheet is stretched
1.1-fold or more in at least one axial direction.
[0136] By stretching, voids having fine powder filler and
incompatible resin as the cores are formed inside the film,
allowing light reflectivity of the film to be increased further,
which is desirable. This is thought to be due to the new formation
of interfaces between aliphatic polyester series resin and void,
void and titanium oxide, and void and incompatible resin, thus
increasing the effects of refractive scatters generated at these
interfaces.
[0137] Furthermore, stretching in two axial directions is
desirable. This is because biaxially stretching increases the
porosity, which allows the light reflectivity of the film to be
raised. In addition, if the film is stretched only uniaxially, the
formed void has only a fibrous morphology elongated in one
direction; however by biaxially stretching, the void is stretched
in both vertical and horizontal directions and has a discoidal
morphology. That is to say, biaxially stretching increases the
surface area of the detachment of the interfaces between the
aliphatic polyester series resin and the fine powder filler, and
aliphatic polyester series resin and incompatible resin, which
promotes bleaching of the film, and as a result, allowing the light
reflectivity of the film to be raised. Further in addition,
anisotropy in the shrinking direction of the film disappears by
biaxially stretching, allowing the heat resistance of the
reflective film to be improved; in addition, the mechanical
strength of the film can be also increased.
[0138] The stretching order of the biaxial stretching is not
limited in particular; for instance, whether simultaneous biaxial
stretching or successive stretching does not matter. After
melt-film-forming using a stretching equipment, stretching in the
MD by roll-stretching and then stretching in the TD by
tenter-stretching may be carried out, and biaxial stretching may be
carried by tubular stretching or the like.
[0139] For the stretch ratio of the film in the case described
above, stretching 5-fold or more as surface area ratio is
desirable, and stretching 7-fold or more is more desirable. By
stretching 5-fold or more in surface area ratio, a porosity of 10%
or greater can be realized, by stretching 7-fold or more, a
porosity of 20% or greater can be realized, and by stretching
7.5-fold or more, a porosity of 30% or greater can be realized.
[0140] The stretching temperature when stretching a cast sheet is
preferably a temperature within a range from on the order of the
glass transition temperature (Tg) of the resin to (Tg+50.degree.
C.); for instance, in the case of a lactic acid series polymer, 50
to 90.degree. C. is desirable. If the stretching temperature is in
this range, a film with a high film-forming stability can be
obtained without the film rupturing during stretching. In addition,
since stretching orientation is high, which allows the porosity to
be large, a film having high reflectance and at the same time
suppressed elastic modulus can be obtained.
[0141] After stretching as described above, the film may be
heat-treated as necessary with suitable methods and conditions.
Manufacturing Method for a Bilayer Film Provided with a Resin Layer
A and a Resin Layer B
[0142] In the following, a manufacturing method for a film having a
bilayer constitution provided with a resin layer A and a resin
layer B will be described.
[0143] An aliphatic polyester series resin composition A is
manufactured similarly to described above.
[0144] Meanwhile, an aliphatic polyester series resin composition B
comprising a fine powder filler, other additives and the like as
necessary mixed with an aliphatic polyester series resin is
manufactured. Concretely, the resin composition B can be obtained
by adding a fine powder filler to an aliphatic polyester series
resin, as necessary further adding an additive such as an oxidation
inhibitor, mixing with a ribbon blender, tumbler, Henschel mixer or
the like, and then kneading at a temperature equal to or higher
than the melting point of the resin using a Banbury mixer, a
uniaxial or biaxial extruder, or the like.
[0145] However, the resin composition B can be also obtained by
adding to the aliphatic polyester series resin, given amounts of
the fine powder filler and the additives, or the like, with
separate feeders or the like. In addition, a so-called master batch
can be manufactured, comprising the fine powder filler, the
additives and the like, pre-mixed at high concentrations in the
aliphatic polyester series resin, and it is also possible to obtain
a resin composition B at the desired concentration by mixing this
master batch and the aliphatic polyester series resin.
[0146] Then, it suffices that the aliphatic polyester series resin
composition A and the aliphatic polyester series resin composition
B described above are each supplied to separate extruders, heated
and melted at temperatures equal to the melting points of each
resin or higher, flown together into a T-die for two species and
two layers use, extruded from the slit-shaped discharge port of the
T-die into a laminate-shape, and solidified by tight contact with a
cooling roll to form a cast film. In so doing, the size of the
disperse phase can be controlled by adjusting the extrusion
temperature of the extruder and the screw rotation speed of the
extruder. Note that the extrusion conditions and the like are the
same as in the case of a monolayer film.
[0147] Then, stretching and heat treatments of the obtained cast
film are the same as in the case of a monolayer film.
Applications
[0148] Although the present reflective film, when used still in
film shape, is particularly useful as a reflective film for large
liquid crystal televisions or the like, it can be also used
suitably as a reflective plate obtained by covering a metal plate
(for instance, aluminum plate, stainless plate, zinc-plated steel
plate and the like) or a resin plate. This reflective plate is
useful as a reflective plate used in, for instance, liquid crystal
display devices such as a liquid crystal displays, illumination
instruments, illuminated signs and the like.
[0149] A manufacturing method for such a reflective plate will be
described below by giving one example.
[0150] As methods for covering a metal plate or a resin plate with
the reflective film, methods using an adhesive, methods of
heat-fusing without using an adhesive, methods of adhering via an
adhesive sheet, methods of extrusion coating, and the like, exist
and are not limited in particular. For instance, it is possible to
coat with an adhesive of the polyester series, polyurethane series,
epoxy series or the like, the surface on the side of the metal
plate or the resin plate (collectively referred to as "metal plate
or the like") where the reflective film is to be pasted, and paste
the reflective film.
[0151] In such a method, a generally used coating equipment such as
a reverse roll coater or a kiss roll coater is used to coat with an
adhesive the surface of a metal plate or the like where the
reflective film is to be pasted so that the adhesive film thickness
is on the order of 2 .mu.m to 4 .mu.m after drying. Next, drying
and heating of the coated surface is carried out with a infrared
radiation heater and a hot air furnace, and while holding the
surface of the metal plate or the like at a given temperature, a
roll laminator is used immediately for covering the plate with the
reflective film and cooling, allowing a reflective plate to be
obtained.
[0152] In this case, if the surface of the metal plate or the like
is held at 210.degree. C. or lower, the light reflectivity of the
reflective plate can be maintained high. Note that the surface
temperature of the metal plate or the like is preferably
160.degree. C. or higher.
EXAMPLES
[0153] Hereinafter, examples will be shown to describe the present
invention more concretely; however, the present invention is not
limited to these, and a variety of applications are possible within
limits not departing from the technical thoughts of the present
invention.
[0154] Note that the measurement and the evaluations shown in the
examples were performed as described below. Here, receiving (flow)
direction of the film is represented with MD, and the direction
perpendicular thereto with TD.
Measurements and Evaluation Methods
[0155] (1) Film-Forming Ability
[0156] In each Example and Comparative Example, when a reflective
film was film-formed, the die drool attachment state of the port
lip portion of the T-die and the pimply skin appearance state of
the film surface were observed, and evaluation of film-forming
ability was conducted based on the following evaluation criteria.
However, the notations "circle" and "triangle" were at practical
levels or above.
(Evaluation Criteria)
[0157] Circle: no appearance of die drool was observed on the lip
portion and no appearance of pimply skin was observed on the film
surface either, even after six hours from the beginning of the
film-forming of the reflective film. Triangle: appearance of die
drool was observed on the lip portion but no appearance of pimply
skin was observed on the film surface after six hours from the
beginning of the film-forming of the reflective film. Cross:
appearance of die drool was observed across the entire width of the
lip portion at after three hours from the beginning of the
film-forming of the reflective film. Moreover, drop-shaped pimply
skins were also observed on the film surface, in some cases
generating holes during stretching.
[0158] (2) Mean Diameter of the Disperse Phase Comprising
Incompatible Resin
[0159] The neighborhood of the center of the film cross section (in
the range of center.+-.25 .mu.m in the thickness direction) was
photographed enlarged at 1,000-fold magnification with a scanning
electron microscope, then, a drawing of the disperse phase traced
on a tracing film was image processed with an image analysis
software (Image-Pro Plus manufactured by Media Cybernetics Inc.) to
determine the mean equivalent circle diameter, which served as the
mean diameter of the disperse phase.
[0160] Here, the equivalent circle diameter was determined as the
diameter of a circle having the same surface area as the projected
surface area of the disperse phase.
[0161] (3) Porosity (%)
[0162] The density of the film prior to stretching (represented as
"non-stretched film density") and the density of the film after
stretching (represented as "stretched film density") were measured
and substituted in the following formula to determine the porosity
of the film.
porosity (%)={(non-stretched film density-stretched film
density)/non-stretched film density}.times.100
[0163] (4) Reflectance (%)
[0164] A spectrophotometer ("U-4000", manufactured by Hitachi,
Ltd.) was fitted with an integrating sphere to measure the
reflectance with respect to light a wavelengths of 700 nm and 550
nm.
[0165] Note that prior to the measurement, the photometer was set
so that the reflectance of alumina white board was 100%.
[0166] (5) Dynamic Storage Modulus (E')
[0167] Dynamic viscoelasticity was measured in the longitudinal
direction using a viscoelasticity spectrometer DVA-200
(manufactured by IT Keisoku K.K.), with measurement temperatures in
the range of -100.degree. C. to 150.degree. C., under the
conditions of 10 Hz oscillation frequency, 0.1% distortion,
2.degree. C./minute temperature rise rate and 2.5 cm chuck spacing.
The numerical value at 23.degree. C. was read as the dynamic
storage modulus (E'). Note that the film was cut accurately to a
size of 4 mm horizontal.times.60 mm vertical to serve as
sample.
[0168] (6) Fold-Processability
[0169] The reflective plates manufactured in Examples 8-11 and
Comparative Example 4 were fold-processed into a U letter shape
(width dimension of the opening interior: 6.00 mm; depth: 5.5 mm)
to serve as sample for evaluation.
[0170] This sample for evaluation was left for three hours in a hot
air-circulating oven thermally adjusted to 85.degree. C. then taken
out to measure the width dimension of the opening interior with a
pin gauge.
[0171] The dimension measurement values were substituted in the
following formula to calculate the amount of change in the width of
the opening interior, and evaluation of fold-processability was
carried out based on the following evaluation criteria.
[0172] However, the notations "circle" and "triangle" were at
practical levels or above.
Amount of change in the width of the opening interior=width
dimension of opening interior before heating-width dimension of
opening interior after heating
(Evaluation Criteria)
[0173] Circle: amount of change in the width of the opening
interior is less than 0.05 mm Triangle: amount of change in the
width of the opening interior is 0.05 mm or greater but 0.10 mm or
less Cross: amount of change in the width of the opening interior
exceeds 0.10 mm
Example 1
Preparation of Resin Composition
[0174] Pellets of a lactic acid series polymer with a weight
average molecular weight of 160,000 (NW3001D, manufactured by
NatureWorks LLC; L isomer content: 98.5%; D isomer content: 1.5%),
pellets of rutile-type titanium oxide by the chlorine method
process (Ti-Pure R-105, manufactured by Du Pont K.K.) and pellets
of polypropylene (Novatech PP FY-4, manufactured by Japan
Polypropylene Corporation; MFR=5 g/10 min) were mixed in a mass
proportion of 33:50:17 to form a mixture.
[0175] With respect to 100 parts in mass of this mixture, 2.5 parts
in mass of anti-hydrolysis agent (bis(dipropyl
phenyl)carbodiimide), furthermore, 3.5 parts in mass of a
styrene-ethylene/butylene-styrene block copolymer of the type
introduced with a butadiene component (Dynalon 8630P: manufactured
by JSR Corporation, butadiene/styrene/ethylene/butylene=1/14/30/55
percent in weight) as SEBS series compound were added and mixed,
and then pelletized using a biaxial extruder to prepare a so-called
master batch.
[0176] This master batch and the above-mentioned lactic acid series
polymer were mixed in a mass proportion of 60:40 to prepare a resin
composition.
[0177] (Preparation of Film)
[0178] The obtained resin composition was supplied to an extruder
heated to 200.degree. C. and kneaded at 200.degree. C. using this
extruder, next, the resin composition in molten state was extruded
into sheet-shape from a T-die and solidified by cooling to obtain a
film.
[0179] The obtained film was roll-stretched 2.3-fold at 65.degree.
C. in the MD and then further tenter-stretched 3-fold at 84.degree.
C. in the TD to perform biaxial stretching, furthermore, was
heat-treated at 140.degree. C., to obtain a 230 .mu.m-thick
reflective film.
[0180] Evaluation of the mean diameter of the disperse phase
comprising the incompatible resin, the porosity, the reflectance
and the dynamic storage modulus was carried out for the obtained
reflective film. The results are shown in Table 1. In addition,
measurements of the degree of brilliance and brightness were also
carried out, the results of which are shown in Table 2.
Example 2
[0181] A reflective film was obtained similarly to Example 1,
except for the point that 3.5 parts in mass of glycidyl
metacrylate-ethylene series copolymer (Bond First 7M: manufactured
by Sumitomo Chemical Co., Ltd.; glycidyl
metacrylate/ethylene/methyl acrylate=6:64:30 percent in weight) was
added instead of the SEBS series compound in the preparation of
resin composition of Example 1.
[0182] The same evaluation as Example 1 was carried out on the
obtained reflective film. The results are shown in Table 1.
Example 3
[0183] A reflective film was obtained similarly to Example 1,
except for the point that 3.5 parts in mass of
styrene-ethylene/butylene-styrene block copolymer of the type
introduced with a glycidyl metacrylate group
(styrene/ethylene/butylene/glycidyl metacrylate=2/63/28/7 percent
in weight) was added as the SEBS series compound in the preparation
of resin composition of Example 1.
[0184] The same evaluation as Example 1 was carried out on the
obtained reflective film. The results are shown in Table 1.
Example 4
[0185] A reflective film was obtained similarly to Example 1,
except for the point that SEBS series compound (Dynalon 8630P:
manufactured by JSR Corporation) along with glycidyl
metacrylate-ethylene series copolymer (Bond First 7M: manufactured
by Sumitomo Chemical Co., Ltd.) were added respectively, at 1.7
parts in mass each, in the preparation of resin composition of
Example 1.
[0186] The same evaluation as Example 1 was carried out on the
obtained reflective film. The results are shown in Table 1.
Example 5
[0187] A reflective film was obtained similarly to Example 1,
except for the point that pellets of lactic acid series polymer
with a weight average molecular weight of 160,000 (NW3001D:
manufactured by NatureWorks LLC; L isomer content: 98.5%; D isomer
content: 1.5%), rutile-type titanium oxide from a chlorine method
process (Ti-Pure R-105: manufactured by Du Pont K.K.) and
polypropylene pellets (Novatech PP FY-4: manufactured by Japan
Polypropylene Corporation) were mixed at a proportion in mass of
42:50:8 to obtain a mixture, in the preparation of resin
composition of Example 1.
[0188] The same evaluation as Example 1 was carried out on the
obtained reflective film. The results are shown in Table 1.
Example 6
Preparation of Resin Composition A
[0189] Pellets of lactic acid series polymer with a weight average
molecular weight of 160,000 (NW3001D: manufactured by NatureWorks
LLC; L isomer content: 98.5%; D isomer content: 1.5%), rutile-type
titanium oxide from a chlorine method process (Ti-Pure R-105:
manufactured by Du Pont K.K.) and polypropylene pellets (Novatech
PP FY-4: manufactured by Japan Polypropylene Corporation: MFR=5
g/10 min) were mixed at a proportion in mass of 33:50:17 to form a
mixture.
[0190] With respect to 100 parts in mass of this mixture, 2.5 parts
in mass of anti-hydrolysis agent (bis(dipropyl
phenyl)carbodiimide), furthermore, 3.5 parts in mass of a
styrene-ethylene/butylene-styrene block copolymer of the type
introduced with a butadiene component (Dynalon 8630P: manufactured
by JSR Corporation, butadiene/styrene/ethylene/butylene=1/14/30/55
percent in weight) as SEBS series compound were added and mixed,
and then pelletized using a biaxial extruder to prepare a so-called
master batch.
[0191] This master batch and a lactic acid series polymer were
mixed in a mass proportion of 60:40 to prepare resin composition
A.
[0192] (Preparation of Resin Composition B)
[0193] Pellets of the obtained lactic acid series polymer (NW3001D)
and the rutile-type titanium oxide (Ti-Pure R-105) described above
were mixed at a proportion in mass of 99:1 to form a mixture. With
respect to 100 parts in mass of this mixture, 3.5 parts in mass of
the anti-hydrolysis agent described above was added and mixed, and
then pelletized using a biaxial extruder to prepare a so-called
master batch.
[0194] This master batch and a lactic acid series polymer were
mixed in a mass proportion of 60:40 to prepare resin composition
B.
[0195] (Preparation of Film)
[0196] The resin compositions A and B were each supplied to
separate extruders A and B heated to 200.degree. C., melt-kneaded
at 200.degree. C. in each extruder, then, flown together into a
T-die for two species and two layers use, extruded into a
sheet-shape so as to have the bilayer constitution B layer/A layer,
and solidified by cooling to form a layered film. The obtained
layered film was roll-stretched 2.3-fold at 65.degree. C. in the MD
and then further tenter-stretched 3-fold at 84.degree. C. in the TD
to perform biaxial stretching, furthermore, was heat-treated at
140.degree. C. to obtain a 230 mm-thick reflective film (A layer:
210 .mu.m; B layer: 20 .mu.m).
[0197] Evaluation of the mean diameter of the disperse phase
comprising the incompatible resin, the porosity, the reflectance
and the dynamic storage modulus was carried out for the obtained
reflective film. The results are shown in Table 1. In addition,
measurements of the degree of brilliance and brightness were also
carried out, the results of which are shown in Table 2.
[0198] In so doing, regarding porosity inside the A layer, the
resin composition A was supplied to extruder A and a monolayer film
having the A layer only (thickness: 210 .mu.m) was obtained
according to the operations described above to carry out the
evaluation.
[0199] The evaluation of degree of brilliance was carried out
according to JIS Z 8741 by matching the incidence angle thereof and
the light receiving angle to 60.degree.. However, light irradiation
was performed on the side of the surface for reflection use, that
is to say, the B layer side of the reflective film, to measured the
degree of brilliance. The "digital variable angle gloss meter model
UGV-5DP (manufactured by Suga Test Instruments Co., Ltd.
Instruments)" was used for the measurement.
[0200] The reflectance was measured similarly to Example 1;
however, light irradiation was performed on the side of the surface
for reflection use, that is to say, the B layer side of the
reflective film.
[0201] For the measurement of the brightness, the manufactured
reflective film was integrated inside a 26-inch liquid crystal
backlight unit (manufactured by SAMSUNG CORPORATION, LTA260W-02),
CCFL, a diffusion plate, a diffusion sheet and a brightness
improvement sheet were stacked in this order and a luminance meter
(manufactured by Topcon Engineering K.K., BM-7) was used to carry
out measurement of the central brightness, which served as the
measurement value. In so doing, the distance between the backlight
unit and the luminance meter was 0.5 m.
[0202] Note that as a reference, evaluation of the degree of
brilliance and brightness was also carried out for the monolayer
reflective film obtained in Example 1. The results are shown in
Table 2.
Comparative Example 1
[0203] A reflective film was obtained similarly to Example 2,
except for the point that the glycidyl metacrylate-ethylene series
copolymer was not mixed in the preparation of resin composition of
Example 2. The same evaluation as Example 1 was carried out on the
obtained reflective film. The results are shown in Table 1.
Comparative Example 2
[0204] A reflective film was obtained similarly to Example 1,
except for the point that 3.5 parts in mass of polyethyleneglycol
(manufactured by Nacalai Tesque Inc.; molecular weight: 4,000) was
added instead of the SEBS series compound in the preparation of
resin composition of Example 1.
[0205] The same evaluation as Example 1 was carried out on the
obtained reflective film. The results are shown in Table 1.
Comparative Example 3
Preparation of Resin Composition A
[0206] Pellets of lactic acid series polymer with a weight average
molecular weight of 160,000 (NW3001D: manufactured by NatureWorks
LLC; L isomer content: 98.5%; D isomer content: 1.5%), rutile-type
titanium oxide from a chlorine method process (Ti-Pure R-105:
manufactured by Du Pont K.K.) were mixed at a proportion in mass of
50:50 to form a mixture. With respect to 100 parts in mass of this
mixture, 2.5 parts in mass of anti-hydrolysis agent (bis(dipropyl
phenyl)carbodiimide) was added and mixed, and then pelletized using
a biaxial extruder to prepare a so-called master batch. This master
batch and a lactic acid series polymer were mixed in a mass
proportion of 60:40 to prepare resin composition A.
[0207] (Preparation of Resin Composition B)
[0208] Pellets of the lactic acid series polymer (NW3001D)
described above and the rutile-type titanium oxide (Ti-Pure R-105)
described above were mixed at a proportion in mass of 99:1 to form
a mixture.
[0209] With respect to 100 parts in mass of this mixture, 3.5 parts
in mass of the anti-hydrolysis agent described above was added and
mixed, and then pelletized using a biaxial extruder to prepare a
so-called master batch.
[0210] This master batch and a lactic acid series polymer were
mixed in a mass proportion of 60:40 to prepare resin composition
B.
[0211] (Preparation of Film)
[0212] The resin compositions A and B were each supplied to
separate extruders A and B heated to 200.degree. C., melt-kneaded
at 200.degree. C. in each extruder, then, flown together into a
T-die for two species and two layers use, extruded into a
sheet-shape so as to have the bilayer constitution B layer/A layer,
and solidified by cooling to form a layered film.
[0213] The obtained layered film was roll-stretched 2.5-fold at
65.degree. C. in the MD and then further tenter-stretched 3-fold at
78.degree. C. in the TD to perform biaxial stretching, furthermore,
was heat-treated at 140.degree. C. to obtain a 150 .mu.m-thick
reflective film (A layer: 135 .mu.m; B layer: 15 .mu.m). The same
evaluation as Example 1 was carried out on the obtained reflective
film. The results are shown in Table 1.
Example 7
Preparation of Film
[0214] A reflective film was obtained similarly to Example 6,
except for the point that a 150 .mu.m-thick reflective film (A
layer: 135 .mu.m; B layer: 15 .mu.m) was obtained in the
preparation of film of Example 6.
[0215] The same evaluation as Example 1 was carried out on the
obtained reflective film. In so doing, regarding porosity inside
the A layer, the resin composition A was supplied to extruder A and
a monolayer film having the A layer only (thickness: 135 .mu.m) was
obtained according to the operations described above to carry out
the evaluation. The results are shown in Table 1.
Example 8
Preparation of Reflective Plate
[0216] A SUS304 plate (thickness 0.2 mm) was covered by the
following procedure with the reflective film obtained in Example 1
to obtain a reflective plate.
[0217] The SUS304 plate surface was coated with a commercialized
polyester series adhesive so that the adhesive film thickness is on
the order of 2 .mu.m to 4 .mu.m after drying. Next, drying and
heating of the coated surface was carried out with a infrared
radiation heater and a hot air furnace, and while holding the
surface temperature of the SUS304 plate at 180.degree. C., a roll
laminator was used immediately for covering the plate with the
reflective film and cooling, to obtain a reflective plate.
[0218] Evaluation of fold-processability was performed for the
obtained reflective plate. The results are shown in Table 3.
Example 9
Preparation of Reflective Plate
[0219] A reflective plate was obtained similarly to Example 8,
except for the point that SUS304 plate (thickness: 0.2 mm) was
covered with the reflective film obtained in Example 5 to obtain
the reflective plate in the preparation of reflective plate of
Example 8. The same evaluation as Example 8 was carried out on the
obtained reflective plate. The results are shown in Table 3.
Example 10
Preparation of Reflective Plate
[0220] A reflective plate was obtained similarly to Example 8,
except for the point that SUS304 plate (thickness: 0.2 mm) was
covered with the reflective film obtained in Example 6 to obtain
the reflective plate in the preparation of reflective plate of
Example 8. The same evaluation as Example 8 was carried out on the
obtained reflective plate. The results are shown in Table 3.
Example 11
Preparation of Reflective Plate
[0221] A reflective plate was obtained similarly to Example 8,
except for the point that SUS304 plate (thickness: 0.2 mm) was
covered with the reflective film obtained in Example 7 to obtain
the reflective plate in the preparation of reflective plate of
Example 8. The same evaluation as Example 8 was carried out on the
obtained reflective plate. The results are shown in Table 3.
Comparative Example 4
Preparation of Reflective Plate
[0222] A reflective plate was obtained similarly to Example 8,
except for the point that SUS304 plate (thickness: 0.2 mm) was
covered with the reflective film obtained in Comparative Example 3
to obtain the reflective plate in the preparation of reflective
plate of Example 8. The same evaluation as Example 8 was carried
out on the obtained reflective plate. The results are shown in
Table 3.
TABLE-US-00001 TABLE 1 Mean dispersed Dynamic particle storage
Reflectance Film forming diameter modulus (%) ability (.mu.m)
Porosity (%) (GPa) 700 nm 550 nm Example 1 .largecircle. 0.9 40 1.8
99.3 99.9 2 .DELTA. 2.8 45 1.7 99.1 99.7 3 .largecircle. 1.8 46 1.7
99.3 99.9 4 .largecircle. 1.5 44 1.8 99.2 99.8 5 .largecircle. 0.8
33 1.9 99.3 99.9 6 .largecircle. 0.8 (A layer) 40 2.4 99.5 100 7
.largecircle. 0.9 (A layer) 39 2.4 99.0 99.8 Comparative 1 X 5.1 41
1.8 98.7 99.6 Example 2 .DELTA. 5.2 39 1.9 98.8 99.6 3
.largecircle. -- (A layer) 28 4 98.4 99.6
TABLE-US-00002 TABLE 2 Degree of Brightness brilliance (cd/m.sup.2)
Example 1 23.8 7650 6 82.9 7840
TABLE-US-00003 TABLE 3 Amount of change in the width of the
Fold-processability opening interior (mm) Assessment Example 8 0.03
.smallcircle. 9 0.05 .DELTA. 10 0.04 .smallcircle. 11 0.03
.smallcircle. Comparative 4 0.14 x example
[0223] As is clear from Table 1, the reflective films of Example 1
to 7 had high light reflectivity with reflectances of 99.0% or
greater with respect to light at both wavelengths of 700 nm and 500
nm. In addition, the reflective films of Example 1 to 7 were found
to have satisfactory film-forming abilities at practical use levels
or grater. In addition, the reflective films of Example 1 to 7 were
found to have store elastic moduli suppressed to 3.0 Gpa or
below.
[0224] Meanwhile, the reflective films of Comparative Example 1 to
3 had reflectances with respect to light at 700 nm wavelength of
less than 99.0%; in addition, the reflective film of Comparative
Example 1 was also found to be poorer than the reflective films of
Example 1 to 7 regarding film-forming ability.
[0225] Since the mean diameter of the disperse phase was less than
3 .mu.m, the surface area of the interface between the voids formed
by stretching and the aliphatic polyester series resin could be
secured thoroughly, and furthermore, the formed bubbles were
compact, the reflective films of Example 1 to 7 were assumed to
have satisfactory reflection capability and film-forming
ability.
[0226] In addition, as is clear from Table 2, the reflective film
of Example 6 was found to have improved light reflectivity compared
to the reflective film of Example 1. This is assumed to be due to
the front brightness becoming high owing to the degree of
brilliance, that is to say, the normal reflectivity becoming all
the more higher.
[0227] In addition, as is clear from Table 3, compared to the
reflective plate of Comparative Example 4, the reflective plates of
Example 8 to 11 had an amount of shrinkage in the width of the
opening interior of 0.10 mm or less, that is to say, were found to
have excellent fold-processability. This is assumed to be due to
the porosity being adjusted to 30% or higher at the same time as
the dynamic storage modulus being adjusted to 3.0 Gpa or lower.
* * * * *